The empire of Wu was one of the Ten States 十國 (902-979) that controlled southern China during the first half of the ninth century, the so-called Five Dynasties period 五代 (907-960). Because its founder was called Yang Xingmi 楊行密 (852-905, posthumous title Emperor Taizu 吳太祖, r. 902-905), it is also called Yang-Wu 楊吳, not least to discern it from other dynasties of that name. The capital of Wu was Guangling 廣陵 (i.e. Yangzhou 揚州, Jiangsu), called prefecture of Jiangdu 江都府. The empire covered the territory of what is today Jiangxi, as well as parts of Jiangsu, Anhui and Hubei.
Yang was of humble origin, but rose to the position of a high officer under the military commissioner (jiedushi 節度使) of Huainan 淮南 (north of modern Jiangsu), Gao Pian 高駢, who made him regional inspector (cishi 刺史) of Luzhou 廬州. Yang showed his military talent and power during the fights between the various warlords in the Yangtze-Huainan area (like Gao Pian, Qin Yan 秦彥, Bi Shiduo 畢師鐸 and Sun Ru 孫儒), and occupied the lower Yangtze area. In 892 he was appointed military commissioner of Huainan and engaged in several fierce campaigns against the empire of Later Liang 後梁 (907-923) in the north, and Wu-Yue 吳越 (907-978) in the southeast. Yang increased his territorial possessions considerably.
Although the region of the lower Yangtze area was very rich and abundant by natural resources, the permanent warfare contributed to the devastation of this region. From 902 on, when he was officially enfeoffed as king of Wu 吳, he started to reconstruct the economy. After his dead in 905, his sons and successors were controlled by mighty generals like Zhang Hao 張顥 and Xu Wen 徐溫. These two murdered Yang Wo 楊渥 (886-908, posthumous title Emperor Liezu 吳烈祖, "reigned" 905-908) and made Yang Longyin 楊隆演 (also called Wei 渭, 897-920, posthumous title Emperor Gaozu 吳高祖, r. 908-920) military commissioner, and Xu Wen also killed Zhang Hao, so that he was from then on the most powerful person in the empire. In 919 Yang Longyin adopted the title of king of Wu. His younger brother Yang Pu 楊溥 (901-938, posthumous title Emperor Rui 吳睿帝, r. 920-937) proclaimed himself emperor in 927.
Xu Wen's foster-son Xu Zhihao 徐知浩 deposed Yang Pu and founded his own dynasty called the Great Qi 大齊 (i.e. Southern Tang 南唐, 937-975) in 937.